在DNA复制和修复过程中染色体面临挑战

Before a cell can divide, it must accurately replicate all of its chromosomes, including the DNA and its associated histone and non-histone proteins.  This process begins at numerous origins of replication during the S phase of the cell cycle in each of a cell’s chromosomes simultaneously. Certain nucleotides can act as origins of replication, but these sequences are not well defined - especially in complex, multi-cellular, eukaryotic species. The length of DNA that spans an origin of...

An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork.   Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication forks, one in...

In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...

The process of chromosome duplication during cell division requires genome-wide disruption and re-assembly of chromatin. The chromatin structure must be accurately inherited, reassembled, and maintained in the daughter cells to ensure lineage propagation.
The basic unit of the chromatin is the nucleosome, consisting of DNA wrapped around octameric histone proteins and short stretches of linker DNA separating individual nucleosomes. The histone proteins within the nucleosome have their...

An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork.   Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication forks, one in...

In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...